1590s, Coniacke, "wine produced in Cognac," the region in western France. The sense of "brandy" is 1755, shortened from 17c. cognac brandy, which was distilled from cognac wine. The place name is from Medieval Latin Comniacum, from the personal name Cominius and the Gallo-Roman suffix -acum.

1640s, from Latin cognatus "of common descent," from com- "together" (see co-) + gnatus, past participle of gnasci, older form of nasci "to be born" (see genus). Words that are cognates are cousins, not siblings. As a noun, from 1754.

mid-14c., from Anglo-French conysance "recognition," later, "knowledge," from Old French conoissance "acquaintance, recognition; knowledge, wisdom" (Modern French connaissance), from past participle of conoistre "to know," from Latin cognoscere "to get to know, recognize," from com- "together" (see co-) + gnoscere "to know" (see notice (n.)). The -g- was restored in English spelling 15c. and has gradually affected the pronunciation, which was always "con-." The old pronunciation lingered longest in legal use.

early 15c., "company of soldiers," from Middle French cohorte (14c.) and directly from Latin cohortem (nominative cohors) "enclosure," meaning extended to "infantry company" in Roman army (a tenth part of a legion) through notion of "enclosed group, retinue," from com- "with" (see co-) + root akin to hortus "garden," from PIE *ghr-ti-, from root *gher- (1) "to grasp, enclose" (see yard (n.1)). Sense of "accomplice" is first recorded 1952, American English, from meaning "group united in common cause" (1719).

late 13c., "close-fitting cap," from Old French coife "skull-cap, cap worn under a helmet, headgear" (12c., Modern French coiffe), from Late Latin coifa "a cap, hood" (source of Italian cuffia, Spanish cofia, escofia), of West Germanic origin (compare Old High German kupphia, Middle High German kupfe "cap").

1847, from French coiffeur "hairdresser," from coiffer "to dress hair," from Old French coife, originally, "inner part of the helmet" (see coif (n.)). A woman hairdresser would be properly a coiffeuse.

c. 1300, "a wedge," from Old French coing (12c.) "a wedge; stamp; piece of money; corner, angle," from Latin cuneus "a wedge." The die for stamping metal was wedge-shaped, and the English word came to mean "thing stamped, a piece of money" by late 14c. (a sense that already had developed in French). Compare quoin, which split off from this word 16c. Modern French coin is "corner, angle, nook." Coins were first struck in western Asia Minor in 7c. B.C.E.; Greek tradition and Herodotus credit the Lydians with being first to make and use coins of silver and gold.

late 14c., "currency, money," from Old French coignage, from coignier "to coin" (see coin (n.)). Meaning "act or process of coining money" is from early 15c.; sense "deliberate formation of a new word" is from 1690s, from a general sense of "something invented" (c. 1600).

1705, "be identical in substance or nature," but from 1640s as a verb in English in Latin form, "occupy the same space, agree in position," from Medieval Latin coincidere (used in astrology), literally "to fall upon together," from Latin com- "together" (see co-) + incidere "to fall upon" (in- "upon" + cadere "to fall;" see case (n.1)). From 1809 as "occur at the same time." Related: Coincided; coinciding.

c. 1600, "exact correspondence in substance or nature," from French coincidence, from coincider, from Medieval Latin coincidere (see coincide). From 1640s as "occurrence or existence during the same time." Meaning "a concurrence of events with no apparent connection" is from 1680s, perhaps first in writings of Sir Thomas Browne.